AGRICULTURE
University of Alberta Students Launch Space Weather Satellite
Ex-Alta 1 is part of the QB50 mission, coordinated by the von Karmen Institute (VKI), in Brussels, Belgium, and
funded by the European Commission. The QB50 Mission is to launch a constellation of CubeSats built by dozens of universities from around the world to collect scientific data from the thermosphere (200-380 kilometre altitude).
According to VKI, “QB50 is an international project that is launching a constellation of 28 CubeSats to investigate the mid to lower thermosphere. The 28 CubeSats are designed and manufactured by students at universities around the world, on five different continents. The lower thermosphere is the least explored region of the atmosphere, and these CubeSats provide the perfect means to conduct in-situ measurements of this region.”
Inside Ex-Alta 1
The Ex-Alta 1 satellite is developed per standardized CubeSat units (1U=10x10x10 cm) and weighs less than 1.33 kg (3 lbs) per U. About the size of a loaf of bread, Ex-Alta 1 is three standard units for a total size of 10x10x30 cm and weighs 2.64 kg (5.82 lbs).
Constructed at the University of Alberta by a team of nearly 50 undergraduate and graduate students in the university’s AlbertaSat group, along with professors from the Faculties of Science and Engineering, the Ex-Alta 1 satellite is equipped with three science payloads. The payloads include a multi-needle Langmuir probe to measure the density of electrons in the lower thermosphere, a dosimeter to monitor ionizing radiation and a digital miniaturized fluxgate magnetometer developed at the university to measure fluctuations in the magnetic field. The three science payloads operate independently, however the data they will generate form complementary datasets.
The satellite also includes a power system, batteries and boards to distribute power as well as turn systems on and off and a computer subsystem to manage and collect data and send to the radio. The Athena on-board computer for cube satellites, part of the open source Open CubeSat Platform (OCP), was designed and built by senior undergraduate students at the University of Alberta. The satellite is also equipped with a 60 cm deployable boom that extends the magnetometer away from the spacecraft.
Ex-Alta 1 also incorporates a GPS navigation system provided by NovAtel® to identify its position and update the time onboard the satellite.
The clocks on board the satellite will drift somewhat over an extended period of time. The precise time available from the NovAtel receiver will be used to correct for this drift for accurate scientific monitoring.
Charles Nokes, Project Manager of Ex-Alta 1 project at the University of Alberta, explains, “Members of our team contacted NovAtel early in the design process. The company executives were excited to participate in the project and immediately sent two OEM615™ units to use so that we had one to fly and one to test. It is really great the way NovAtel worked with us. This is a student volunteer project, not an official academic program; it’s something that students work on in their spare time. Our partnership with NovAtel has been great. Having a company like NovAtel’s support helped make this project possible.”
The OEM615 Global Navigation Satellite System (GNSS) positioning system is able to track GPS, GLONASS, Galileo and BeiDou. It’s easy to integrate, has low power consumption (1 W), is lightweight (24 g) and is small in size (71 mm x 46 mm x 11 mm).
The positioning system is located on the anti-ram side, the side that points opposite the direction of the Ex-Alta 1 satellite’s motion. (Note: the ram side of the satellite faces in the direction of the satellite’s motion.)
Nokes continues, “Integrating the GPS and the antenna was an interesting process because we needed to have access to GPS signals to test the connection to the antenna and its functionality. We did not have access to a GPS simulator, so we ended up testing the GPS in real-time on the roof.”
The team designed a sealed portable container that could transport the satellite and facilitate the interface. Once on the roof, the GPS antenna on the satellite acquired signals from GPS satellites overhead. They initialized the OEM615 unit and verified that the spacecraft could obtain a lock on the location and the time. Once launched into the ionosphere, the student-led team sent commands to turn on the GPS in orbit. The environment on orbit in the ionosphere has much higher levels of radiation. The GPS unit may be affected by interactions with large numbers of high energy particles.
One of the primary objectives of the mission of the Ex-Alta 1 is to study the interaction between energy coming from the sun and its effect on the Earth’s magnetic field, within the ionosphere, as a result of electrical currents driven by space weather. Space weather also affects the radiation environment in space with potentially catastrophic impacts on satellites. To that end, the radiation dosimeter will measure variations in radiation levels in low Earth orbit (the altitude between the Earth’s surface and 2,000 km), by measuring the number of electrically charged particles in the Earth’s magnetic field. To monitor the magnetic field, the magnetometer will be deployed at the end of a 60 cm boom to study the Earth’s magnetic field in low Earth orbit.
“Low Earth orbit is poorly understood at this time,” says Nokes. “In particular, our satellite will be flying through the South Atlantic Anomaly where we’ll see some interesting phenomena in the way of radiation belts penetrating to lower altitudes. We’ve characterized the systems on the ground and are continuing to improve the technology. We have an idea of what to expect in space, though making clean magnetic measurements requires moving the magnetometer away from the electrical noise generated by satellite subsystems—that’s also why we’ll deploy the magnetometer on a boom away from the satellite.”
The satellite data from Ex-Alta 1 and the rest of the CubeSat constellation will provide scientists with unprecedented insight into the low Earth orbit activity and the effects of space weather in the mid to lower thermosphere—all for an impressively reasonable cost.
The Cost of Constellations
Low cost is one of the huge advantages of CubeSat missions. The components that make up the Ex-Alta 1 satellite cost about $120,000 USD (the value of the satellite itself). There is considerable ground support equipment that is also required as well as hundreds of volunteer hours to build and test the satellite.
“A more realistic number to describe the cost of the entire mission is around $800,000 USD, including the launch cost, the costs associated with project and mission level systems engineering, and of course goodwill and value of volunteer hours,” says Nokes. “Normally, the cost to launch a 3U CubeSat is on the order of $200,000-300,000 USD, depending on the launcher and the required orbit. Through funding from the European Commission, the QB50 program provided a subsidized launch opportunity hence we paid only $48,000 USD for our launch.”
The largest portion of the funding and support for Ex-Alta 1, over $80,000 USD, came from the University of Alberta through the Faculty of Engineering’s Engineering Student Project Fund and the Faculty of Science. Significant funding was also drawn from two crowd sourcing campaigns, as well as a contribution of $75,000 USD from the Canadian Space Agency, a launch subsidy and mission level project management from VKI and the QB50 program and the in-kind donation of two receivers from NovAtel.
As part of the QB50 mission, 28 CubeSats of the QB50 constellation, including Ex-Alta 1, were integrated into 11 NanoRacks 6U deployers earlier this year.
On April 18, 2017, the QB50-ISS group was launched with the Orbital ATK Cygnus spacecraft on a cargo resupply mission to
the International Space Station (ISS) atop a United Launch Alliance Atlas 5 rocket from Cape Canaveral Air Force Station, Florida.
Once on the ISS, the crew used the NanoRacks CubeSat Deployer (NRCSD) to deploy the QB50 satellites. Once deployed, the satellites began to orbit the Earth in the thermosphere, a layer of atmosphere that extends from about 95 km to 500 km. Of note, the ISS maintains an orbit about 403 km (250 miles) above Earth.
The satellite deployed at 2:55 a.m. Mountain time on May 26, 2017 from the International Space Station. Students at the university ground stations heard the satellite’s beacons and announced operational status. CubeSat mission durations and orbital life vary, though it’s hoped that Ex-Alta 1 will orbit for up to 18 months. Upon mission completion, the CubeSats fall to Earth, burning up harmlessly in the atmosphere.
The AlbertaSat team is already working on its second satellite, the Ex-Alta 2, which will be entered in the 4th Canadian Satellite Design Challenge in 2018. The Ex-Alta 2 will fly in-house developed technologies and experiments as scientific payloads and focus on open sourced cube satellite systems.